1. Field of the Invention
The present invention relates, in general, to air purifiers and, more particularly, to an air purifier for use in providing dean air by removing dust, bacteria and contaminants from the air.
2. Description of the Related Art
As is well known to those skilled in the art, an air purifier is used to provide purified clean air by removing dust, bacteria and contaminants from the air. The air purifier is provided with a dust collecting, unit to collect dust, and the like. In the dust collecting unit, dust particles electrically charged by corona discharge of an ionizer are collected by electrostatic attraction of a collector having a polarity opposite to a polarity of the charged dust particles.
FIG. 1 is a side sectional view of a conventional air purifier. As shown in FIG. 1, the conventional air purifier includes a pre-filter 102, an ionizer 104, a collector having horizontal partitions 106a, a HEPA (High-Efficiency Particulate Air) filter 108, and a fan 110. The pre-filter 102 acts primarily to filter relatively large dust particles sucked through the pre-filter by the fan 110. The ionizer 104 functions to charge the dust particles electrically to bear a positive. polarity by corona discharge between a discharge electrode 104b and ground electrodes 104a, positioned at both sides of the discharge electrode 104b. The collector 106 has a plurality of horizontal partitions 106a bearing a negative polarity. When the positively charged dust particles flow between the horizontal partitions 106a of the collector, the dust particles are adsorbed and collected on the negatively charged horizontal partitions by electrostatic attraction. The HEPA filter 108 functions to filter fine dust, bacteria or fungi not filtered by the horizontal partitions 106a of the collector.
However, in the conventional air purifier, the HEPA filter functioning to filter microparticles, such as fine dust, bacteria or fungi, must have a microstructure necessary for filtering the microparticles, so the HEPA filter generates high resistance against air currents circulated through the air purifier, and thus causes a high degree of air pressure loss, even though the HEPA filter has high air-purifying efficiency. Due to the high degree of air pressure loss caused by the HEPA filter, purified air cannot be distributed to areas distant from the air purifier. In addition, the amount of impurities deposited on the HEPA filter are increased as operating time goes by, so that the air pressure loss caused by the HEPA filter with the impurities is increased. Therefore, the problem of air pressure loss caused by the HEPA filter worsens as the operating time of the air purifier increases. When air pressure in the air purifier is forcibly increased in an effort to solve the problem of air pressure loss caused by the HEPA filter, operational noise of the air purifier is undesirably increased, disturbing people near the air purifier.